def fb(n):
    res = [0 for _ in range(n + 1)]
    print(len(res))

    for i in range(0, n + 1):
        if i < 2:
            res[i] = i
        else:
            res[i] = res[i - 1] + res[i - 2]

    return res[-1]


# n = int(input())
n = 3
print(fb(n))
